Sight-glass mountings which are built into pipelines or onto containers before or after valves or slide gates, serve for the observation of the flowing medium as regards colour, consistency or degree of fouling. Known sight-glass mountings are produced by casting and exhibit a tubular section onto the open opposite ends of which first fixing flanges are cast in one piece or are welded on or fitted on. In the central section on diametrically opposite sides of the cylindrical shell, pipe stubs with second flanges are likewise cast on in one piece or welded on. The said first flanges serve for building the sight-glass mounting into the pipeline, and the said second flanges serve for the attachment of the glass discs which in general are attached in a removable manner by means of a flange ring with the interposition of sealing rings in order to be able to exchange them in case of damage or to clean them.
The production of the known sight-glass mounting by the dead-mould casting process is comparatively costly because for each size a special model must be manufactured and the casting must be effected singly. Since it is again always a question of different materials from which the sight-glass mountings must consist, that is, a material of the same kind as the pipeline into which it is to be built, a comparatively costly individual manufacture is necessary. Since the wall thickness of the cast products is furthermore comparatively great, the use of a greater amount of material is necessary. In addition to this the pipe stubs onto which the transparent discs are flanged, form dead spaces in which dirt is deposited, so that the view through the sight-glass with time becomes impaired.
In the German Offenlegungsschrift No. 29 33 939 a more economical manufacture of such sight-glass mountings is made possible by plain bearing areas for the glass discs being provided, which are moulded in one piece onto the section of pipe in the region round the openings. By this means dead spaces may be avoided, so that the view through the glass discs even after fairly long use of the mounting does not get impaired by deposited dirt.
In the case of this known sight-glass mounting a section of the pipeline into which the sight-glass mounting is to be built, may be employed for its production. This section then consists of the same material as the pipeline and therefore no problems result through the mating of different materials. It has less thickness of wall than a cast product, and hence demands less material and consequently is already cheaper. The formation of the bearing areas for the glass discs of the sight-glass mounting, in the region of the openings provided at diametrically opposite sides of the pipe shell, which are to be covered over by the discs to form a seal, may be effected in a manner which is very simple in manufacturing technique, by pressing, which reduces the costs of manufacture.
The object of this invention is to create a sight-glass mounting for building into pipelines running horizontally or onto horizontal outlets from containers, which is cheap to produce and in which no deposition of dirt can occur, which would cloud the view through the sight-glass mounting or make cleaning difficult. The diameter of the glass discs in that case is larger than the diameter of the section of pipe of the mounting.